In recent years, researches and developments have been made on technology for allowing a user to three-dimensionally perceive images hereinafter also referred to as stereo display technology). Such stereo display technology includes a technique of allowing a user to perceive an image stereoscopically by controlling parallax between a left eye image and a right eye image (hereinafter also collectively referred to as image for stereoscopic vision).
However, the user's stereoscopic perception of the image (hereinafter also referred to as stereoscopic vision) is burdensome to the user. Hence, the stereo display technology that alleviates the burden on the user is desired. Note that in the following description, an image to be stereoscopically viewed is also referred to as a stereoscopic vision image or a stereoscopic vision object.
With respect to this, Patent Literature 1 describes an image processing device that automatically adjusts the depth of a stereoscopic vision image. Here, the depth is a degree of protrusion or withdrawal of an observation target perceived by a user from the screen. Thus, the observation target is displayed at a depth suitable for the user observing the stereoscopic vision image, and the burden on the user is reduced.